What do systematic reviews say?

IUI in a stimulated cycle vs TI

IUI in stimulated cycles showed no clear difference in multiple pregnancy rate per couple compared with TI (low certainty).

• Assisted reproductive technologies for male subfertility 2016 · Cochrane Headline outcomes only
  OR 3.15 [0.12, 79.69]
  Studies not reported
  Low

Intervention not reported

It is very uncertain whether the intervention changes multiple pregnancy ‐ Clomiphene citrate 5 days versus clomiphene… (very low certainty).

• Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome 2016 · Cochrane Headline outcomes only
  OR 0.33 [0.03, 3.2]
  1 study · 220 participants
  Very low

Antioestrogen vs placebo

The review found no eligible studies for this question.

• Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome 2016 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Antioestrogen vs antioestrogen

It is very uncertain whether antioestrogen changes clomiphene citrate versus tamoxifen ‐ Multiple pregnancy compared with antioestrogen (very low certainty).

• Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome 2016 · Cochrane Headline outcomes only
  OR 2.34 [0.34, 16.04]
  3 studies · 567 participants
  Very low

Day 3 vs Day 2 embryo transfer following IVF or ICSI

Day 3 showed no clear difference in multiple pregnancy rate per woman compared with day 2 embryo transfer following IVF or ICSI (moderate certainty).

• Day three versus day two embryo transfer following in vitro fertilization or intracytoplasmic sperm injection 2016 · Cochrane Headline outcomes only
  RR 1.12 [0.86, 1.44]
  8 studies · 1837 participants
  Moderate

Low‐dose aspirin vs placebo or no treatment

Low‐dose aspirin showed no clear difference in multiple pregnancy (on ultrasound) compared with placebo or no treatment (low certainty).

• Aspirin for in vitro fertilisation 2016 · Cochrane Headline outcomes only
  RR 0.67 [0.37, 1.25]
  2 studies · 656 participants
  Low

Ultrasound‐guided embryo transfer vs clinical touch

Ultrasound‐guided embryo transfer showed no clear difference in multiple pregnancy (per woman randomised) compared with clinical touch (moderate certainty).

• Ultrasound versus 'clinical touch' for catheter guidance during embryo transfer in women 2016 · Cochrane Headline outcomes only
  OR 1.13 [0.87, 1.45]
  8 studies · 3379 participants
  Moderate

DHEA or testosterone vs placebo/no treatment

It is very uncertain whether DHEA or testosterone changes multiple pregnancy ‐ DHEA compared with placebo/no treatment (very low certainty).

• Androgens (dehydroepiandrosterone or testosterone) for women undergoing assisted reproduction 2015 · Cochrane Headline outcomes only
  OR 3.23 [0.13, 81.01]
  5 studies · 267 participants
  Very low
• Androgens (dehydroepiandrosterone or testosterone) for women undergoing assisted reproduction 2015 · Cochrane Headline outcomes only
  OR 3.09 [0.48, 19.98]
  3 studies · 292 participants
  Very low

hCG vs GnRH agonist

It is very uncertain whether hCG changes multiple pregnancy rate per pregnancy compared with gnRH‐a (very low certainty).

• Synchronised approach for intrauterine insemination in subfertile couples 2014 · Cochrane Headline outcomes only
  OR 0.15 [0.02, 1.38]
  4 studies · 74 participants
  Very low

hCG vs LH surge

It is very uncertain whether hCG changes multiple pregnancy rate per pregnancy compared with LH surge (very low certainty).

• Synchronised approach for intrauterine insemination in subfertile couples 2014 · Cochrane Headline outcomes only
  OR 1.12 [0.17, 7.6]
  2 studies · 42 participants
  Very low

u‐hCG vs r‐hCG

u‐hCG showed no clear difference in multiple pregnancy rate per pregnancy compared with r‐hCG (low certainty).

• Synchronised approach for intrauterine insemination in subfertile couples 2014 · Cochrane Headline outcomes only
  OR 0.99 [0.4, 2.47]
  2 studies · 109 participants
  Low

IUI vs FSP

IUI showed no clear difference in multiple pregnancy per couple compared with FSP (low certainty).

• Intrauterine insemination versus fallopian tube sperm perfusion for non‐tubal infertility 2013 · Cochrane Headline outcomes only
  OR 0.62 [0.29, 1.32]
  7 studies · 908 participants
  Low

GnRHa depot vs GnRHa daily injection

GnRHa depot showed no clear difference in multiple pregnancy rates compared with gnRHa daily injection (low certainty).

• Depot versus daily administration of gonadotrophin‐releasing hormone agonist protocols for pituitary down regulation… 2013 · Cochrane Headline outcomes only
  OR 1.1 [0.49, 2.46]
  4 studies · 132 participants
  Low

Herbal preparations plus medication vs medication

• Herbal preparations for uterine fibroids 2013 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  Low

Natural cycle IVF vs standard IVF

It is very uncertain whether natural cycle IVF changes multiple pregnancy per woman compared with standard IVF (very low certainty).

• Natural cycle in vitro fertilisation (IVF) for subfertile couples 2013 · Cochrane Headline outcomes only
  OR 0.76 [0.25, 2.31]
  2 studies · 527 participants
  Very low

Repeated single embryo transfer (mixed policies) vs multiple embryo transfer

Repeated single embryo transfer (mixed policies) showed no clear difference in cumulative live birth compared with multiple embryo transfer (low certainty).

• Number of embryos for transfer following in vitro fertilisation or intra‐cytoplasmic sperm injection 2020 · Cochrane Headline outcomes only
  RR 0.95 [0.82, 1.1]
  4 studies · 985 participants
  Low

Repeated single embryo transfer (mixed policies) vs multiple embryo transfer

Repeated single embryo transfer (mixed policies) showed no clear difference in clinical pregnancy rate compared with multiple embryo transfer (low certainty).

• Number of embryos for transfer following in vitro fertilisation or intra‐cytoplasmic sperm injection 2020 · Cochrane Headline outcomes only
  RR 0.95 [0.84, 1.08]
  3 studies · 943 participants
  Low

Repeated single embryo transfer (mixed policies) vs multiple embryo transfer

Repeated single embryo transfer (mixed policies) showed no clear difference in miscarriage rate compared with multiple embryo transfer (low certainty).

• Number of embryos for transfer following in vitro fertilisation or intra‐cytoplasmic sperm injection 2020 · Cochrane Headline outcomes only
  odds ratio 2.14 [0.93, 4.95]
  2 studies · 282 participants
  Low

Single vs multiple embryo transfer

Single may leads to lower live birth compared with multiple embryo transfer (low certainty).

• Number of embryos for transfer following in vitro fertilisation or intra‐cytoplasmic sperm injection 2020 · Cochrane Headline outcomes only
  RR 0.67 [0.59, 0.75]
  12 studies · 1904 participants
  Low

Single vs multiple embryo transfer

Single may leads to lower clinical pregnancy compared with multiple embryo transfer (low certainty).

• Number of embryos for transfer following in vitro fertilisation or intra‐cytoplasmic sperm injection 2020 · Cochrane Headline outcomes only
  RR 0.7 [0.64, 0.77]
  10 studies · 1860 participants
  Low